Ask HN: (again): how would you interview senior developer candidates?

(this is a repost as my first post went unanswered)

Hello HN,

I'm the CTO of a just-launched start-up and looking to hire a senior/lead developer. Although I used to write code for a living, I haven't done so, or hired developers, in a while. So I'm looking for advice on which questions / interview practices are relevant from the candidate's perspective -e.g. not off-putting or off-topic- and from my perspective -i.e. that will give me useful insights on a candidate's skills. Specifically, I want to evaluate coding skills (both actual code practice and the ability to reason about complexity, algorithms, etc.); development practices (architecture design, unit testing, deployment automation, etc.); devops or sysadmin experience; and last but not least, the ability to get things done and deliver projects in an uncertain or shifting context.

Things that I'm considering asking, besides the usual discussion on the candidate's previous experience:

- discussing 2 or 3 "real-world" programming problems to see how the candidate would tackle them

- contribution to open-source projects

- code example (e.g. GitHub profile, or StackOverflow contributions)

Things that are out of the question:

- whiteboard programming and/or academic questions on BST or Dijkstra's algorithm

- pair programming (it will most probably be too early in the development phase to have any meaningful code to work on)

- paid work on an actual project (ditto + complex to organize given France's legislation)

What else should I be asking? What should I avoid? In your experience, what works and what doesn't?

Thanks for your insights.

Note: the job is in Paris, France in case anyone's interested :D